Platelet Inhibitors Reduce Rupture in a Mouse Model of Established Abdominal Aortic Aneurysm

A Phillip Owens, Todd L Edwards, Silvio Antoniak, Julia E Geddings, Eiman Jahangir, Wei-Qi Wei, Joshua C Denny, Yacine Boulaftali, Wolfgang Bergmeier, Alan Daugherty, Uchechukwu K A Sampson, Nigel Mackman

Rupture of abdominal aortic aneurysms causes a high morbidity and mortality in the elderly population. Platelet-rich thrombi form on the surface of aneurysms and may contribute to disease progression. In this study, we used a pharmacological approach to examine a role of platelets in established aneurysms induced by angiotensin II infusion into hypercholesterolemic mice. Administration of the platelet inhibitors aspirin or clopidogrel bisulfate to established abdominal aortic aneurysms dramatically reduced rupture. The mechanism of protection seems to be a reduction in abdominal aortic platelet and macrophage recruitment resulting in decreased active matrix metalloproteinase-2 and matrix metalloproteinase-9. Platelet inhibitors also resulted in reduced plasma concentrations of platelet factor 4, cytokines, and components of plasminogen activation system in mice. To determine the validity of these findings in human subjects, eligible aneurysm patients were retrospectively analyzed using developed and validated algorithms in the electronic medical record database at Vanderbilt University. Similar to mice, administration of aspirin or P2Y12 inhibitors was associated with reduced death among patients with abdominal aortic aneurysm. These results suggest that platelets contribute to abdominal aortic aneurysm progression and rupture.